This invention relates to armor wire splices and in particular, but not exclusively, to methods of making armor wire splices for armored submarine cable containing optical fibres.
An armored submarine cable containing optical fibres may comprise a central strength member about which a plurality of optical fibres is arranged to form a fibre package. The fibre package is arranged within a protective aluminum pressure-resistant tube, and the tube is surrounded by a further strength member comprised, for example, of one or more layers of high tensile steel wires. A tubular copper conductor, for the supply of electrical power to a regenerator, is arranged over the further strength member, and a sheath of plastics insulating material, for example, polyethylene, is extruded over the copper conductor. One or more layers of armor wires, for example galvanized steel wires, are laid up directly or indirectly over the insulating sheath.
When such a cable is damaged in use, for example, or at other times when two armored cable ends have to be jointed, jointing must be carried out in such a manner as to reduce the risk of movement of the optical fibres within the jointed cable, in orrder to prevent strain on the optical fibre splices (joints). A conventional optical fibre cable joint (unarmored) and method of making it is disclosed in U.S. Pat. No. 4,252,405 and can be used to join the optical fibres and further strength member wires of armored cables.
These jointing methods employ ferrule elements with clamping arrangements to secure the further strength member steel wires and a chamber to accommodate optical fibres spliced in a conventional manner. The various ferrule elements are of electrically conductive material to provide electrical continuity between the copper conductor ends, and also effectively reinstate the pressure resistant tube over the fibre splices. A tube of plastic insulation material is arranged over the ferrule and injection moldings between each end thereof and the adjacent plastics sheath ends reinstate the insulant.
In the case of armored cable, the armoring wires must also be spliced or joined in some manner to also reinstate the armoring. A conventional technique known as overlay splicing, which is used in connection with submarine cables having metallic conductors instead of optical fibres, is not suitable for use with optical fibre cables since an armor joint so produced has a large possible elongation which may result in damage to the optical fibres, or the further strength member high tensile steel strands.